This invention relates to a process for removing sulfur in the form of hydrogen sulfide from fluid streams. In another aspect, this invention relates to a composition suitable for use in such process.
The removal of sulfur from fluid streams can be desirable or necessary for a variety of reasons. If the fluid stream is to be released as a waste stream, removal of sulfur from the fluid stream can be necessary to meet the sulfur emission requirements set by various air pollution control authorities. Such requirements are generally in the range of about 10 ppm to 500 ppm of sulfur in the fluid stream. If the fluid stream is to be burned as a fuel, removal of sulfur from the fluid stream can be necessary to prevent environmental pollution. If the fluid stream is to be processed, removal of the sulfur is often necessary to prevent the poisoning of sulfur sensitive catalysts or to satisfy other process requirements.
A variety of methods employing regenerable, solid contact materials are known for removing sulfur from a fluid stream when the sulfur is present as hydrogen sulfide. For example, U.S. Pat. No. 4,088,736 discloses a composition comprising zinc oxide, alumina, and a Group IIA metal which is an effective sorbent for hydrogen sulfide and which possesses the property of being regenerable to the original sorbent state in the presence of oxygen when fully sulfided.
Although the sorbent employed in such methods may effectively adsorb or absorb, or both, hydrogen sulfide from a fluid stream containing hydrogen sulfide, it has been found that many of these sorbents effectively oxidize certain quantities of hydrogen sulfide to sulfur dioxide. The resulting sulfur dioxide is not removed from the fluid stream by the sorbent and, thus, passes through the contact material with the treated fluid stream. This phenomenon is sometimes called sulfur slippage. It is desirable to have a sorption material which has a high capacity to adsorb or absorb, or both, sulfur from a fluid stream and which minimizes the amount of sulfur slippage as well as being regenerable in the presence of oxygen after becoming fully sulfided.